Best Nitric Oxide Lozenges: What to Look For (and Why the Format Matters)

This article contains affiliate links. We only recommend products we have independently researched. Reviewed by the HealthyMag Editorial Team. Last updated: July 2026.

If you have gone looking for a nitric oxide supplement, you have probably noticed something odd: many of the most-researched products are not pills or powders. They are lozenges you let dissolve slowly on your tongue. That is not a marketing gimmick. It reflects a genuine piece of physiology — nitric oxide production actually begins in your mouth. This guide explains why the oral format is rational, what ingredients and quality markers actually matter, and how the three main lozenge brands (CircO2, Neo40, and N1O1) compare on the things that count. We have verified every study we cite, and we are honest about where the evidence is thin.

Why a lozenge? The oral nitric oxide science

Your body makes nitric oxide two ways. The classic pathway uses an enzyme (nitric oxide synthase) in your blood vessel lining to make NO from the amino acid L-arginine. But there is a second, “backup” route that becomes more important as we age and as that enzyme becomes less efficient: the entero-salivary nitrate–nitrite–nitric oxide pathway.

Here is how it works. When you eat nitrate-rich foods (beets, leafy greens), the nitrate is absorbed, and about a quarter of it is actively concentrated back into your saliva. On the surface of your tongue, commensal bacteria — genera such as Neisseria, Prevotella, and Veillonella — reduce that nitrate into nitrite. A 2022 review in the Journal of Dental Research describes this clearly: dietary nitrate “is reduced to nitrite by nitrate reductases expressed in commensal oral bacteria,” with the highest activity on the back of the tongue. That nitrite is then swallowed and further converted into nitric oxide in the body. In short, NO production genuinely begins in the mouth.

The most striking evidence for how important your mouth is comes from mouthwash studies. In a crossover trial of healthy volunteers published in Free Radical Biology and Medicine (Kapil and colleagues, 2013), one week of twice-daily antiseptic mouthwash cut oral nitrite production by roughly 90 percent, dropped circulating plasma nitrite by about 25 percent, and raised blood pressure by 2 to 3.5 mm Hg. When you wipe out the bacteria that live in your mouth, you measurably lose nitric oxide. That is a powerful clue that the oral cavity is a real control point for this system — and it is the logic behind delivering NO precursors as a slow-dissolving lozenge rather than a capsule you swallow whole.

The concept has been tested directly. In a placebo-controlled crossover study of 30 unmedicated hypertensive adults (Houston and Hays, The Journal of Clinical Hypertension, 2014), a single NO-generating lozenge — the formula sold as Neo40 — lowered resting blood pressure by about 4 mm Hg systolic and 5 mm Hg diastolic within 20 minutes, with larger reductions at 60 minutes. That is a small, short-term study, but it is a real, peer-reviewed human trial of an actual lozenge product, which is more than most supplement categories can claim.

For a broader look at how dietary nitrate affects circulation and stamina, see our deep dive on beetroot juice for blood pressure and endurance, which covers the same pathway from the food side.

What to look for in a nitric oxide lozenge

Not all lozenges are built the same. Here is what separates a thoughtful formula from a gummy with fairy dust.

An evidence-based NO source. There are three ingredients with real human support:

• Dietary nitrate (usually beet root). The clearest evidence in this whole category. In a 2015 randomized trial in Hypertension (Kapil and colleagues, 68 hypertensive patients), daily dietary nitrate lowered clinic blood pressure by 7.7/2.4 mm Hg over four weeks.
• Sodium nitrite. The active ingredient in the lozenges that showed the fast blood-pressure drop in the Houston trial. It is essentially the “downstream” molecule your mouth would have made anyway.
• L-citrulline. Feeds the enzyme pathway by raising L-arginine. A 2021 meta-analysis in the British Journal of Nutrition (Smeets and colleagues) found longer-term L-citrulline improved flow-mediated vasodilation by about 0.9 percentage points, though effects on blood pressure itself were inconsistent.

“Reducing” helper ingredients. Vitamin C (ascorbic acid) and plant polyphenols like hawthorn berry help convert nitrite into NO. These are not filler — they are part of the chemistry that makes the lozenge work in the mouth.

Disclosed doses, not just a “proprietary blend.” The single biggest red flag in this category is a formula that hides individual ingredient amounts behind a blend name. You cannot judge whether you are getting a meaningful dose if the label will not tell you.

Third-party testing. Because sodium nitrite is a potent, dose-sensitive ingredient, independent testing (USP, NSF, or a published certificate of analysis) matters more here than in most supplements. Look for it, and be skeptical when a brand only advertises “GMP manufacturing,” which is a baseline requirement, not proof of independent verification.

A dissolve-in-mouth format. The whole point is oral contact time. A lozenge you chew and swallow in ten seconds partly defeats the purpose.

The main lozenge products compared

Three products dominate this niche. Here is an honest read on each.

CircO2 (Advanced Bionutritionals). A fast-dissolving lozenge built around a broad, disclosed-style blend: beet root powder, L-citrulline, hawthorn berry, vitamin C, vitamin B12, magnesium, and sodium nitrite. It is the most “kitchen sink” of the three, combining dietary nitrate, an enzyme-pathway precursor, and reducing agents in one tablet. It is vegan, non-GMO, and — a nice touch — ships with saliva test strips so you can see your NO status. It carries a solid ~3.9/5 average user rating. Its weakness is the same as most supplements: the exact milligram amounts inside the NO blend are not fully transparent.

Neo40 (Nathan Bryan / HumanN). This is the lozenge formula tested in the Houston 2014 blood-pressure trial, which is a genuine credibility marker — few supplements can point to a peer-reviewed human study of the actual product. It combines beet root, hawthorn, vitamin C, L-citrulline, and sodium nitrite. It tends to be the priciest of the three, and current retail formulas may differ from the exact trial version, so the study supports the concept more than any specific bottle you buy today.

N1O1 (branded “N1O1,” sometimes written N101; created by Dr. Nathan S. Bryan). A more minimalist, purist design: essentially sodium nitrite plus magnesium ascorbate (a vitamin C source) engineered to trigger NO release via a redox reaction with saliva, deliberately without depending on your oral bacteria. That is an interesting advantage if antibiotics or heavy mouthwash use have disrupted your microbiome. It is the leanest formula — no beet root or citrulline — so you are betting on the nitrite-to-NO chemistry alone.

A necessary caveat on the science: Dr. Bryan’s group ran a rigorous randomized, double-blind trial of a sodium-nitrite NO lozenge in COVID-19 patients (Molnar, Somberg, and Bryan, The American Journal of Medicine, 2023) and it showed no benefit on hospitalization, intubation, or symptom duration. We include this because good faith requires it: these lozenges have plausible mechanisms and some positive blood-pressure data, but they are not miracle cures, and there are no published head-to-head trials pitting CircO2, Neo40, and N1O1 against each other.

Prices are approximate and change frequently; check current listings.

Our pick & where to buy

How to use them

The mechanics of a NO lozenge are simple, but a few habits meaningfully affect results:

• Let it dissolve — do not chew and swallow. Oral contact time is the entire point. Most products dissolve over roughly 5 to 6 minutes.
• Mind your mouthwash. Given what the mouthwash studies showed, avoid antibacterial rinses close to your lozenge (or reconsider daily use altogether if you rely on this pathway).
• Consistency matters more than timing. The clearest blood-pressure benefits in the nitrate literature came from daily use over weeks, not one-off doses. Many people take it in the morning or before exercise.
• Pair it with a nitrate-rich diet. Leafy greens and beets feed the same system. A lozenge supplements that food base; it does not replace it.
• Use the test strips if your product includes them. They turn an abstract “am I responding?” question into a visible answer.

Realistic expectations & safety

Set your expectations at the level the evidence supports. The best documented effect is a modest, often short-lived reduction in blood pressure — on the order of a few mm Hg in the studies above — plus potential improvements in circulation and exercise tolerance that overlap with what dietary nitrate does. These are real but incremental effects, not dramatic transformations. And remember the null COVID trial: a plausible mechanism does not guarantee a benefit for every outcome. Head-to-head lozenge trials simply do not exist yet.

On safety: sodium nitrite is a real drug-like ingredient, so respect the labeled dose and do not double up across products. If you take blood-pressure medication, nitrates (like nitroglycerin), or erectile-dysfunction drugs (PDE5 inhibitors such as sildenafil), the additive blood-pressure-lowering effect can be significant — talk to your doctor first. The same goes for pregnancy, and for infants, who should never be given nitrite-containing products. If you are managing a heart condition, our overview of CoQ10 for heart health and statin users is a useful companion read on where supplements do and do not have supporting evidence.

Frequently Asked Questions

Do nitric oxide lozenges work?

There is genuine, if limited, human evidence. A placebo-controlled trial of a NO-generating lozenge (the Neo40 formula) lowered blood pressure by roughly 4/5 mm Hg within 20 minutes in hypertensive adults, and the broader dietary-nitrate literature consistently shows small blood-pressure reductions. That said, effects are modest, some trials (including a COVID-19 study) showed no benefit, and there are no head-to-head comparisons between brands. They can help, but they are not miracle products.

Are lozenges better than nitric oxide pills?

For NO specifically, the lozenge format has a rational advantage: nitric oxide production begins in the mouth, where saliva and oral bacteria convert nitrate and nitrite into NO. A slow-dissolving lozenge maximizes that oral contact time, whereas a capsule bypasses the mouth entirely. That is why several of the most-studied NO products are lozenges. Pills built around L-arginine or L-citrulline work through a different (enzyme) pathway and are not necessarily worse — just different.

What is the best nitric oxide lozenge?

There is no single winner backed by direct comparison data. For a broad, well-rounded formula at a fair price, we lean toward CircO2, which combines beet nitrate, L-citrulline, and reducing agents and includes saliva test strips. Neo40 is the formula with a published human blood-pressure trial. N1O1 is the minimalist, bacteria-independent option. The “best” depends on whether you prioritize formula breadth, published data, or microbiome independence.

CircO2 vs Neo40 — which should I choose?

Both are quality lozenges from credible sources with overlapping ingredients (beet root, L-citrulline, hawthorn, sodium nitrite, vitamin C). Neo40’s edge is that its formula was used in a peer-reviewed blood-pressure study, but it is typically the more expensive product. CircO2 is generally cheaper, adds B12 and magnesium, and includes NO saliva test strips. If cost and self-monitoring matter most, CircO2; if product-specific published data matters most, Neo40.

How do you use nitric oxide lozenges?

Let the lozenge dissolve slowly in your mouth rather than chewing and swallowing it, since oral contact time drives the NO conversion. Use it daily for the most consistent effect, avoid antibacterial mouthwash around the same time, and pair it with a diet rich in leafy greens and beets. If your product comes with saliva test strips, use them to confirm you are responding.

Are nitric oxide lozenges safe?

For most healthy adults, yes, at the labeled dose. But sodium nitrite is a potent ingredient, so do not exceed the recommended amount or stack multiple NO products. Use caution and consult a doctor if you take blood-pressure medication, nitrates, or ED drugs (PDE5 inhibitors), as the combined blood-pressure-lowering effect can be significant. Avoid in pregnancy and never give nitrite products to infants.

Does mouthwash affect nitric oxide lozenges?

It can. Research shows antiseptic mouthwash cut oral nitrite production by about 90 percent and raised blood pressure by 2 to 3.5 mm Hg, because it kills the tongue bacteria that convert nitrate to nitrite. If your lozenge relies on that bacterial step (like beet-nitrate formulas), heavy mouthwash use may blunt its effect. Products designed to work without oral bacteria, such as N1O1, are less affected.

How long do nitric oxide lozenges take to work?

Acute blood-pressure effects have been measured within 20 to 60 minutes in trials. But the more meaningful, sustained benefits in the nitrate literature came from daily use over several weeks. Think of it as both a quick, short-lived bump and a longer-term habit, not a one-time fix.

The Bottom Line

Nitric oxide lozenges rest on a real piece of physiology: NO production genuinely starts in your mouth, and the oral format is designed to take advantage of that. The best products use evidence-based ingredients — dietary nitrate, sodium nitrite, or L-citrulline — plus reducing agents like vitamin C and hawthorn, disclose their doses, and ideally offer third-party testing. Human data support modest blood-pressure and circulation benefits, but the effects are incremental, not dramatic, and direct brand-versus-brand trials do not exist. Of the three established players, CircO2 is our value pick for a broad, well-supported formula with built-in feedback, Neo40 has the strongest product-specific study, and N1O1 is the smart minimalist choice if your oral microbiome is compromised. Whichever you choose, use it daily, skip the antibacterial mouthwash, keep eating your greens, and check with your doctor if you take cardiovascular medications.

Sources

1. Morou-Bermúdez E, Torres-Colón JE, Bermúdez NS, Patel RP, Joshipura KJ. Pathways Linking Oral Bacteria, Nitric Oxide Metabolism, and Health. Journal of Dental Research. 2022. https://pmc.ncbi.nlm.nih.gov/articles/PMC9124908/
2. Kapil V, Haydar SMA, Pearl V, Lundberg JO, Weitzberg E, Ahluwalia A. Physiological role for nitrate-reducing oral bacteria in blood pressure control. Free Radical Biology and Medicine. 2013;55:93-100. https://pmc.ncbi.nlm.nih.gov/articles/PMC3605573/
3. Houston M, Hays L. Acute Effects of an Oral Nitric Oxide Supplement on Blood Pressure, Endothelial Function, and Vascular Compliance in Hypertensive Patients. The Journal of Clinical Hypertension. 2014;16(7):524-529. https://pmc.ncbi.nlm.nih.gov/articles/PMC8031495/
4. Kapil V, Khambata RS, Robertson A, Caulfield MJ, Ahluwalia A. Dietary Nitrate Provides Sustained Blood Pressure Lowering in Hypertensive Patients: A Randomized, Phase 2, Double-Blind, Placebo-Controlled Study. Hypertension. 2015;65(2):320-327. https://pubmed.ncbi.nlm.nih.gov/25421976/
5. Molnar J, Somberg JC, Bryan NS. The Efficacy of Nitric Oxide Generating Lozenges on Outcome in Newly Diagnosed COVID-19 Patients: A Randomized Clinical Trial. The American Journal of Medicine. 2023. https://pmc.ncbi.nlm.nih.gov/articles/PMC10290177/
6. Smeets ETHC, Mensink RP, Joris PJ. Effects of L-citrulline supplementation and watermelon consumption on longer-term and postprandial vascular function and cardiometabolic risk markers: a meta-analysis of randomised controlled trials in adults. British Journal of Nutrition. 2021. https://pmc.ncbi.nlm.nih.gov/articles/PMC9592950/